Hi, I have an issue I wanted your opinions on. I hope someone might be able to help....
I have a 20L tank which is has substrate and is well planted - No C02 Injection. Internal filter, Temp running at 26.C - Tank has been running for a good 6 months, no issues at all. Water Parameters always been ok. Tested yesterday - PH 7.0, Ammonia 0 Nitrite 0 Nitrate 50 - on my tap water test is is also high and the water is hard in this area.
In September 2020, I added four male Dumbo Guppies - QT at pet shop and ok on arrival. Placed in tank and noticed on in December that one of the males had extensive damage to his fin. I put this down to fin nipping as it was a male only tank. Reduced the water temp to 24.C as I was told this calmed them down and added some females. I noticed after a day that one of the females had a fungal infection and was coated with white fungus on her mouth and body. I took her out and the others and they died within a few days of each other. I treated the whole tank with ESHA2000 and all was ok.
After a period of time, I added some more females and the males were happy.
Yesterday I noticed that one of the males fins appeared to be nipped again. on closer inspection of the rest of the fish, one female appears to be nipped also. Water tested, and treated with ESHA2000 again. Tomorrow will be day 3 of the treatment of which I intend to end, do a 50% water change and retreat for another cycle. I didn't QT them, I have treated the whole tank as I only have 7 guppies in this tank.
I have posted elsewhere and am told it could be fin rot or columnaris, I dont think it is columnaris, apart from the fin damage, the fish are well, feeding okay, swimming happily, poo is not discoloured or any different. No white spots or raised lumps, swelling or anything like that.
What could this be, what might be causing it and is my treatment the right one? Any help that could be given would be appreciated.
The photo below is of the guppy who was treated in December. He sadly jumped the tan and died over night.
The fins look nipped to me. If it was fin rot the edges would be ragged and whitish, but those are clean nips out of the fin. I think to be honest your tank is too small for them. The minimum recommended for guppies is around 50-60 litres. 20L is really toossmall for fish.